Devices using various kinds of media, such as optical disks, magnetic disks, magneto-optical disks, or the like have been known in the art as data storage devices. In particular, hard disk drives (HDDs) have been widely used as storage devices of computers. Moreover, HDDs have found widespread application to moving image recording/reproducing apparatuses, car navigation systems, digital cameras, cellular phones, or the like in addition to computers.
A HDD comprises a head slider for accessing (reading or writing) a magnetic disk and an actuator for supporting the head slider and swinging to move the head slider above the magnetic disk. The actuator comprises a suspension on which the head slider is fixed. The airflow viscosity between the head slider and the spinning magnetic disk balances the force applied to the head slider by the suspension to allow the head slider to fly over the magnetic disk.
Solder ball bonding (SBB) has been known in the art as a technique for electrically connecting wirings of a slider and a suspension. A conventional SBB method disposes solder balls between connection terminals of a slider and those of a suspension and reflows them by laser beam to electrically interconnect the connection terminals of the slider and the suspension. The solder balls are reflowed within an atmosphere of inactive gas such as nitrogen (for example, refer to a Japanese Patent Publication No. 2002-251705 “Patent Document 1”).
Recent requests for lead-free materials demand that the above-described solder balls be made of lead-free solder. Lead-free solder has a higher melting point than solder mainly composed of lead. Accordingly, reflowing such solder balls requires high energy. On the other hand, a head element portion on a head slider is a heat-sensitive component and it is important to prevent damage onto the head element portion in a reflow process. Therefore, it is desired to improve the wetting characteristic of solder balls with lower energy. For this improvement in wetting characteristic, it is effective to reduce the oxygen concentration around the solder balls during the reflow process.
The most effective method to reduce the oxygen concentration around the solder balls is to perform the reflow process in a sealed space filled with nitrogen. However, filling the entire room with nitrogen requires much equipment and consumes a huge amount of nitrogen gas. Accordingly, it is necessary to lower the oxygen concentration around the solder balls with less equipment and nitrogen. In order to lower the oxygen concentration around the solder balls, or to increase the density of nitrogen to be blown, it is important to blow nitrogen gas uniformly.
A technique has been known that blows out nitrogen gas through a porous member to attain uniform nitrogen gas (for example, refer to the Patent Document 1). However, since interconnection of a head slider and a suspension requires fine and secure interconnection, merely blowing nitrogen gas through a porous member does not exert sufficient effect for improving wetting characteristic. Accordingly, an effective reflow technique is desired for the interconnection of the head slider and the suspension.